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1.
Jing Chao DONG Run Tao LI* Tie Ming CHENG* Department of Bioorganic Chemistry School of Pharmaceutical Sciences Peking University Beijing 《中国化学快报》2001,(12)
Since Daly reported the structure of epibatidine and its potent analgesic activity in 19921, study on the synthesis of epibatidine and its derivatives and relationships between the structure and activity of epibatidine has received much attention2. During the course of our research for the synthesis of epibatidine derivatives, N-boc-2, 5-bis(trimethylsilyl)pyrrolidine 4 was used as the key intermediate to construct the skeleton of epibatidine via the 1, 3-dipolar cycloaddition (Scheme 1). Ac… 相似文献
2.
KBr acts as an efficient and reusable catalyst for the selective and efficient trimethylsilylation of benzylic, primary and secondary aliphatic alcohols and phenols with hexamethyldisilazane. All reactions were performed at room temperature under mild and completely heterogeneous conditions in good to high yields. 相似文献
3.
Odinokov V. N. Savchenko R. G. Nazmeeva S. R. Galyautdinov I. V. 《Russian Chemical Bulletin》2002,51(10):1963-1964
In the reactions of poststerone derivatives and 20-hydroxyecdysone with (trifluoromethyl)trimethylsilane catalyzed by tetrabutylammonium fluoride, the 14-hydroxy group is readily subjected to trimethylsilylation. 相似文献
4.
Hossein A. Oskooie Majid M. Heravi Maryam H. Tehrani Farahnaz K. Behbahani Omid M. Heravi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1729-1737
In this article, a mild and efficient protocol for the trimethylsilylation of various aliphatic and benzylic alcohols and phenols with trimethylsilyl chloride using a catalytic amount of ferric perchlorate at room temperature and relatively short reaction times in good to excellent yields is reported. Direct acetylation of trimethylsilyl ethers catalyzed with Fe(ClO 4 ) 3 .6H 2 O(0.02 mmol)/Fe(ClO 4 ) 3 SiO 2 (0.2 g) using acetic anhydride at ambient temperature is also reported. 相似文献
5.
Ardeshir Khazaei Amin Rostami Fatemeh Mantashlo 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2288-2296
The first catalytic application of p-toluenesulfonyl chloride (p-TsCl) for the efficient and selective trimethylsilylation of various types of hydroxyl groups with hexamethyldisilazane (HMDS) in dichloromethane and desilylation of these compounds in water is reported. The reactions were carried out at room temperature and were found to proceed in good to excellent yields. 相似文献
6.
Hamid Reza Shaterian Nafiseh Fahimi Kobra Azizi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1604-1611
Abstract An eco-friendly and mild protocol for trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel using hexamethyldisilazane has been described. Solvent-free and ambient reaction conditions, easy workup, short reaction times, excellent yields, and reusability of the catalyst are the noticeable features of this methodology. GRAPHICAL ABSTRACT 相似文献
7.
Szmigielski R Surratt JD Vermeylen R Szmigielska K Kroll JH Ng NL Murphy SM Sorooshian A Seinfeld JH Claeys M 《Journal of mass spectrometry : JMS》2007,42(1):101-116
In the present work, we have characterized in detail the chemical structures of secondary organic aerosol (SOA) components that were generated in a smog chamber and result from the photooxidation of isoprene under high-NO(x) conditions typical for a polluted atmosphere. Isoprene high-NO(x) SOA contains 2-methylglyceric acid (2-MG) and oligoester derivatives thereof. Trimethylsilylation, in combination with capillary gas chromatography (GC)/ion trap mass spectrometry (MS) and detailed interpretation of the MS data, allowed structural characterization the polar oxygenated compounds present in isoprene SOA up to 2-MG trimers. GC separation was achieved between 2-MG linear and branched dimers or trimers, as well as between the 2-MG linear dimer and isomeric mono-acetate derivatives thereof. The electron ionization (EI) spectra of the trimethylsilyl derivatives contain a wealth of structural information, including information about the molecular weight (MW), oligoester linkages, terminal carboxylic and hydroxymethyl groups, and esterification sites. Only part of this information can be achieved with a soft ionization technique such as electrospray (ESI) in combination with collision-induced dissociation (CID). The methane chemical ionization (CI) data were used to obtain supporting MW information. Interesting EI spectral differences were observed between the trimethylsilyl derivatives of 2-MG linear and branched dimers or trimers and between 2-MG linear dimer mono-acetate isomers. 相似文献
8.
Isao Hasegawa 《Journal of Sol-Gel Science and Technology》1993,1(1):57-63
Tetracethoxysilane (TEOS) and methyltriethoxysilane (MTEOS) have been co-hydrolyzed in methanolic solutions containing tetramethylammonium ions that only affect polymerization of silicate species (hydrolysis products of TEOS) to form the Si8O
20
8–
cubic octameric silicate species. The effects of water content and TEOS-to-MTEOS molar ratio on the distribution of species formed in the solutions have been investigated with the trimethylsilylation technique and 29Si n.m.r. spectroscopy. Formation of Si8O
20
8–
and the cubic octameric species consisting of both Si(O–)4 and CH3Si(O–)3 units, (CH3)nSi8O
20–n
(8–n)–
(n=1–5), is found in the solutions. The increase of water content in the solutions solely results in increasing yield of Si8O
20
8–
in spite of the presence of hydrolysis products of MTEOS together with those of TEOS, suggesting that water in the solutions plays an important role in the formation of Si8O
20
8–
with the aid of tetramethylammonium ions. The TEOS-to-MTEOS molar ratio varies the distribution that is kept under control by the water content, increasing yields of (CH3)nSi8O
20–n
(8–n)–
(n=1, 2). It is found that the water content and TEOS-to-MTEOS molar ratio determine the reaction conditions effective for the formation of CH3Si(O–)3 unit-containing cubic octameric species. 相似文献
9.
Mauro Rubino Sylvie Milin Antonio D'Onofrio Patrick Signoret Christine Hatté Jérôme Balesdent 《Isotopes in environmental and health studies》2014,50(4):516-530
In this study, we evaluated trimethylsilyl (TMS) derivatives as derivatization reagents for the compound-specific stable carbon isotope analysis of soil amino acids by gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS). We used non-proteinogenic amino acids to show that the extraction–derivatization–analysis procedure provides a reliable method to measure δ13C values of amino acids extracted from soil. However, we found a number of drawbacks that significantly increase the final total uncertainty. These include the following:
production of multiple peaks for each amino acid, identified as di-, tri- and tetra-TMS derivatives;
a number of TMS-carbon (TMS-C) atoms added lower than the stoichiometric one, possibly due to incomplete combustion;
different TMS-C δ13C for di-, tri- and tetra-TMS derivatives.
10.
F. Shirini N. Ghaffari Khaligh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2156-2165
Abstract Succinimide-N-sulfonic acid (SuSA) is easily prepared by the reaction of succinimide with chlorosulfonic acid. This reagent is able to efficiently catalyze the chemoselective trimethylsilylation of alcohols and phenols with hexamethyldisilazane (HMDS). All reactions were performed under mild reaction conditions, giving excellent yields. GRAPHICAL ABSTRACT 相似文献